It looks like, at the moment, the best weblog software options are WordPress and Typo. The former is PHP, the latter Ruby on Rails. Both should run just fine via Apache on MS Windows, assuming support for the language/framework used to build them. I'm not really sure about how well either is supported on IIS -- that's something you'll have to figure out for yourself. Rails, however, comes with its own dedicated webserver called WEBrick, if you want to use that, and it's not a bad choice for Rails applications.
IIS-targeted weblog software tends to be of the obtuse sort, a desktop application that generates static pages that can be uploaded to the server without much in the way of useful features. There are exceptions to this -- they're basically all ASP.NET and expensive, mostly with licenses that target single-user weblogs. Many of the Apache-targeted weblog software options can also be run on IIS, though it often takes a bit of hoop-jumping to get them running on IIS.
In general, the good wiki software all runs on Apache, with IIS support as an afterthought if IIS is supported at all. The best for quick setup and deployment, in my experience, are MediaWiki (the software used by Wikipedia) and TikiWiki (kinda like a lightweight reimplementation of most of MediaWiki). The former is more feature-rich and generally robust. The latter is more portable and easier to set up. Both are excellent, in my experience, despite the fact they're both written in PHP.
There are Ruby-based wikis called Soks and Instiki. I know nothing about them, though they tend to be well-regarded. You may want to evaluate them for yourself. They both work excellently well with WEBrick. I'm sure they work well with Apache as well. IIS -- probably not so much.
Unless you want to settle for C-list software, or write it all yourself, you should probably set up Apache on your MS Windows server (or run it on a Linux/*BSD box). The fact you have MS Windows clients shouldn't require you to use an MS Windows server for their web browsing pleasure. The whole point of the Web is portable, platform nonspecific, easy, universal access for clients. Corporate logo compatibility will have no effect on the technical performance of your solutions.
